Vancouver police are warning the public about multimillion-dollar swindle.

The scam resulted in thefts of $3.1 million in five cases.

"In two of the cases, VPD investigators were able to recover just over $2.5 million of the stolen money," Sgt. Jason Robillard told reporters.

Here's how it works: con artists phone elderly people from a land line claiming to be a police officer or an employee of a jewellery store.

They tell the senior that their credit card had been used fraudulently for a large purchase.

Then the person is informed that police require their help in solving the crime. Next, they're instructed to call 9-1-1 or the bank.

Robillard said the victims picked up the phone, heard a dial tone recording, and did what they were told.

But police believe that the thieves didn't actually disconnect the phone—instead, they played a recording of a dial tone to leave the senior with the impression that they were talking to a banker or the police.

More calls ensued and the victims were convinced to transfer large amounts of money to accounts overseas.

"In these situations, awareness is the key to phone scams like this one," Robillard said. "When you use a hard line, we want you to know that this is possible.

"There is an opportunity for somebody to still be on the other line," he continued. "We want you to consider using a cellphone or to make sure that you're disconnected after you use a hard line."

Police believe there may be additional victims and are asking them to come forward.